Heat Treated Precipitated Silica

ABSTRACT

Process for heat treating precipitated silica to improve stability. Oral care compositions comprising such heat treated precipitated silica abrasives and a stannous ion source.

FIELD OF THE INVENTION

The present invention relates to processes for heat treatment ofprecipitated silica particles and to oral care compositions comprisingsuch treated precipitated silica particles.

BACKGROUND OF THE INVENTION

An effective oral composition can maintain and preserve tooth appearanceby removing dental stains and polishing the teeth. It may clean andremove external debris as well, which can aid the prevention of toothdecay and promote gingival health.

Abrasives in oral compositions aid in the removal of the tightlyadherent pellicle film to which dental stains affix. Pellicle filmusually comprises a thin acellular, glycoprotein-mucoprotein coating,which adheres to the enamel within minutes after teeth are cleaned. Thepresence of various food pigments lodged within the film accounts formost instances of teeth discoloration. An abrasive may remove thepellicle film with minimal abrasive damage to oral tissue, such as thedentin and enamel.

In addition to cleaning, it may be desirable for abrasive systems toprovide polishing of tooth surfaces, as polished surfaces may be moreresistant to ectopic deposition of undesirable components. Toothappearance may be improved by imparting a polished character to theteeth, because the surface roughness, that is, its polish, affects lightreflectance and scattering, which integrally relate to the teeth'svisual appearance. The surface roughness also affects tooth feel. Forexample, polished teeth have a clean, smooth, and slick feel.

Numerous dentifrice compositions use precipitated silicas as abrasives.Precipitated silicas are noted and described in U.S. Pat. No. 4,340,583,Jul. 20, 1982, to Wason, EP Patent 535,943A1, Apr. 7, 1993, to McKeownet al., PCT Application WO 92/02454, Feb. 20, 1992 to McKeown et al.,U.S. Pat. No. 5,603,920, Feb. 18, 1997, and U.S. Pat. No. 5,716,601,Feb. 10, 1998, both to Rice, and U.S. Pat. No. 6,740,311, May 25, 2004to White et al.

While providing effective cleaning of teeth, precipitated silicas inoral compositions may present compatibility problems with key formulaactives, such as stannous ions. These compatibility problems have beenshown to be directly related to surface properties of precipitatedsilicas such as surface area, number of hydroxyl groups, and porosity.

PCT Published Patent Application WO 93/23007 assigned to W.R. Gracediscloses that thermal treatment of precipitated silica at 300-850° C.for 1-3 hours can significantly improve compatibility with CPC orchlorhexidine. Reference is also made to non-fluoride therapeuticagents.

U.S. Pat. No. 4,346,071 (PQ Corp-8/24/87) discloses improved abrasivityby dehydrating then rehydrating silica gel. The silica gel therein washeated to 310° C.

A need exists for an abrasive system that has good compatibility withstannous ions while providing effective and safe cleaning and polishingof dental tissue. In addition, there exists a continuing need forabrasives that can produce superior cleaning and polishing at reducedcosts. The methods and compositions of the present invention related tothe heat treatment of precipitated silica particles may provide one ormore of these advantages. The present invention also relates to oralcompositions containing improved precipitated silica particles andmethods using such oral compositions that may provide better stannousstability.

SUMMARY OF THE INVENTION

It has now been surprisingly found rapid heat treatment of precipitatedsilica particles at high temperature can, without being limited bytheory, reduce the surface hydroxyls while maintaining the innerprecipitated silica structure, resulting in improved stability withstannous ions.

The processes of the present invention therefore include treatingprecipitated silica particles with heat having a temperature of fromabout 800° C. to about 1050° C. for less than 5 minutes. The resultingtreated precipitated silica particles surprisingly exhibit improvedcompatibility with stannous ions and/or improved PCR measurements.

The oral care composition of the present invention comprises heattreated precipitated silica and a stannous ion source. The stannous ionmay be from stannous fluoride or from a stannous salt selected from thegroup consisting of stannous chloride, stannous gluconate, stannousacetate, stannous tartrate, stannous oxalate, stannous sulfate, stannouscitrate, stannous malonate, stannous lactate, stannous phosphate,stannous pyrophosphate, stannous bromide, stannous iodide, andcombinations thereof. The amount of stannous ions may be from about 50ppm to about 15,000 ppm or less than about 10,000 ppm.

In one embodiment, the stannous ions will have a compatibility ofgreater than 80% after two weeks of storage at 25° C. or before use. Inanother embodiment, the compatibility may be greater than 90% at 25° C.or before use.

Also disclosed is a method of reducing plaque, gingivitis, sensitivity,oral malodor, erosion, cavities, calculus, inflammation, and staining byadministering to a subject's oral cavity a composition comprising a heattreated precipitated silica and a stannous ion source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1-A graphical representation of the impact on the Q3 of Z-119silica values when heated for two hours data that is included in Table2, below.

FIG. 2-A graphical representation of the relationship between Q3 valuesand stannous compatibility of Z-119 silica after heat treatment for twohours data that is included in Table 2, below.

FIG. 3-A graphical representation plotting stannous compatibility versusheat treatment of silica at two minutes data that is included in Table2, below.

DETAILED DESCRIPTION OF THE INVENTION

While the specification concludes with claims that particularly pointout and distinctly claim the invention, it is believed the presentinvention will be better understood from the following description.

Definitions

The term “orally acceptable carrier” as used herein means a suitablevehicle or ingredient, which can be used to form and/or apply thepresent compositions to the oral cavity in a safe and effective manner.Such vehicle may include materials such as fluoride ion sources,antibacterial agents, anticalculus agents, buffers, other abrasivematerials, peroxide sources, alkali metal bicarbonate salts, thickeningmaterials, humectants, water, surfactants, titanium dioxide, flavorsystem, sweetening agents, cooling agents, xylitol, coloring agents,other suitable materials, and mixtures thereof.

The term “comprising” as used herein means that steps and ingredientsother than those specifically mentioned can be added. This termencompasses the terms “consisting of and “consisting essentially of.”The compositions of the present invention can comprise, consist of, andconsist essentially of the essential elements and limitations of theinvention described herein, as well as any of the additional or optionalingredients, components, steps, or limitations described herein.

The term “effective amount” as used herein means an amount of a compoundor composition sufficient to induce a positive benefit, an oral healthbenefit, and/or an amount low enough to avoid serious side effects,i.e., to provide a reasonable benefit to risk ratio, within the soundjudgment of a skilled artisan.

The term “oral composition” as used herein means a product that in theordinary course of usage is retained in the oral cavity for a timesufficient to contact some or all of the dental surfaces and/or oraltissues for purposes of oral activity. The oral composition of thepresent invention may be in various forms including toothpaste,dentifrice, tooth gel, tooth powders, tablets, rinse, subgingival gel,foam, mouse, chewing gum, lipstick, sponge, floss, prophy paste,petrolatum gel, or denture product. The oral composition may also beincorporated onto strips or films for direct application or attachmentto oral surfaces, or incorporated into floss.

The term “dentifrice” as used herein means paste, gel, powder, tablets,or liquid formulations, unless otherwise specified, that are used toclean the surfaces of the oral cavity.

The term “teeth” as used herein refers to natural teeth as well asartificial teeth or dental prosthesis.

The term “polymer” as used herein shall include materials whether madeby polymerization of one type of monomer or made by two (i.e.,copolymers) or more types of monomers.

The term “water soluble” as used herein means that the material issoluble in water in the present composition. In general, the materialshould be soluble at 25° C. at a concentration of 0.1% by weight of thewater solvent, preferably at 1%, more preferably at 5%, more preferablyat 15%.

The term “phase” as used herein means a mechanically separate,homogeneous part of a heterogeneous system.

The term “substantially non-hydrated” as used herein means that thematerial has a low number of surface hydroxyl groups or is substantiallyfree of surface hydroxyl groups. It may also mean that the materialcontains less than about 5% total water (free or/and bound).

The term “majority” as used herein means the greater number or part; anumber more than half the total.

The term “median” as used herein means the middle value in adistribution, above and below which lie an equal number of values.

All percentages, parts and ratios are based upon the total weight of thecompositions of the present invention, unless otherwise specified. Allsuch weights as they pertain to listed ingredients are based on theactive level and, therefore, do not include solvents or by-products thatmay be included in commercially available materials, unless otherwisespecified. The term “weight percent” may be denoted as “wt.%” herein.

All molecular weights as used herein are weight average molecularweights expressed as grams/mole, unless otherwise specified.

Heat Treated Precipitated Silica

The present invention utilizes heat treated precipitated silica in oralcompositions, particularly in dentifrice compositions. Many currentdentifrice compositions use silica as a thickening agent as well as anabrasive. Precipitated silicas are made by an aqueous precipitation ordrying process.

Precipitated silicas typically have a BET surface area ranging between30 m^(2/) g and 80 m²/g. BET surface area is determined by BET nitrogenabsorption method of Brunaur et al., J. Am. Chem. Soc., 60, 309 (1938).See also U.S. Pat. No. 7,255,852, issued Aug. 14, 2007 to Gallis.

Silicas with less than about 5% bound and free water may be consideredsubstantially non-hydrated. The total bound and free water can becalculated by totaling two measurements, loss on drying (LOD) and losson ignition (LOI). For loss on drying, performed first, a sample may bedried at 105° C. for two hours, the weight loss being the free water.For loss on ignition, the dried sample then may be heated for one hourat 1000° C., the weight loss being the bound water. The sum of the LODand LOI represents the total bound and free water in the originalsample. For example, a typical precipitated silica, ZEODENT 119(“Z-119”), has a loss on drying of 6.1% and a loss on ignition of 5.1%,for a sum of 11.2% total water. (For another test method, see the UnitedStates Pharmacopeia-National Formulary (USP-NF), General Chapter 731,Loss on Drying and USP-NF, General Chapter 733, Loss on Ignition.)

Several types of hydroxyl (“-OH”) groups (silanols) are present in aprecipitated silica: isolated singles, geminals, and vicinals. Isolated“Q3” is where there is one —OH group on a silicon atom that cannothydrogen bond. Vicinal “Q3” is where there is one —OH group on a siliconatom that can hydrogen bond with another —OH group on an adjacentsilicon atom. Geminal “Q2” is where there are two —OH groups on the samesilicon atom. Also, there are siloxane linkages “Q4” where two siliconatoms are linked together through an oxygen atom. NMR may be used tomeasure the amount of Q2, Q3, and Q4 groups present in a given sample.

A typical precipitated silica measures above 3000 intensity/g andtypically above 3500 silanol density (in intensity/g). The accounting ofsurface hydroxyl groups can be found by using nuclear magnetic resonancespectroscopy (NMR) to measure the silanol density of a particularsilica. Silanols are compounds containing silicon atoms to which hydroxysubstituents bond directly. When a solids nmr analysis is performed onvarious silicas, the silicon signal is enhanced by energy transfer fromneighboring protons. The amount of signal enhancement depends on thesilicon atom's proximity to protons found in the hydroxyl groups locatedat or near the surface. Therefore, the silanol density, stated asnormalized silanol signal intensity (intensity/g), is a measure ofsurface hydroxyl concentration. For example, Huber's ZEODENT 119measures 3716 intensity/g. Test method for silanol density used solidstate nmr with cross polarization with magic angle spinning (5 kHz) andhigh power gated proton decoupling and Varian Unity Plus-200spectrometer with a 7 mm supersonic dual channel probe made by DotyScientific. The relaxation delay was 4 seconds (s) and the contact timewas 3 ms. Number of scans was between 8,000 and 14,000, and theexperimental time frame was 10-14 hours per sample. Samples are weighedto 0.1 mg for normalization procedure. Spectra were plotted in absoluteintensity mode and integrals were obtained in absolute intensity mode.Silanol density is measured by plotting and integrating spectra inabsolute intensity mode.

The surface reactivity of silica, a reflection of the relative number ofsurface hydroxyls, may be measured by a silica's ability to absorbmethyl red from a solution. This measures the relative number ofsilanols. The test is based on the fact that methyl red will selectivelyabsorb on the reactive silanol sites of a silica surface.

Without being bound by theory, it is believed that the heat treatedprecipitated silica according to the processes set forth herein, withits lower number of surface hydroxyl groups, is less reactive thanuntreated precipitated silica. Consequently, the heat treatedprecipitated silica may adsorb less of other components, such asflavors, actives, or cations, leading to better availability for theseother components. For example, dentifrices incorporating heat treatedprecipitated silica have superior stability and availability forstannous. Heat treatment of precipitated silica according to the presentinvention may result in at least about 50%, 60%, 70%, 80%, or 90%compatibility with cations or other components. The cation may be asource of stannous ions.

The tapped density of precipitated silica is typically at most 0.55g/ml. Bulk density and tapped density can be measured by following themethods in the USP-NF, General Chapter 616, Bulk Density and TappedDensity. For bulk density, method 1, Measurement in a Graduated Cylindermay be used; for tapped density, method 2, which uses a mechanicaltapper, may be followed. Bulk density and tapped density represent massto volume ratios of particles (multiple particles confined in a givenspace), and reflect trapped air, porosity, and how particles fittogether in a given space. A true or intrinsic density of a particle(mass to volume ratio of a single particle) of precipitated silicas isat most about 2.0 g/cm³. The specific gravity of precipitated silicasmay be at most about 2.0.

The water absorption of precipitated silicas is typically about 90 g/100g. Water absorption is measured using the J. M Huber Corp. standardevaluation method, S.E.M No. 5,140, Aug. 10, 2004). Oil absorption istypically about 100 ml dibutyl phthalate/100 g precipitated silica. (Oilabsorption is measured according to the method described in U.S. PatentApplication 2007/0001037A1, published Jan. 4, 2007.

Precipitated silicas particles typically have a Mohs hardness of 5.5-6.

The unique surface morphology of heat treated precipitated silica mayresult in more favorable PCR/RDA ratios. The Pellicle Cleaning Ratio(PCR) is a measure of the cleaning characteristics of a dentifrice. TheRadioactive Dentine Abrasion (RDA) is a measure of the abrasiveness ofthe heat treated precipitated silica when incorporated into adentifrice.

PCR values are typically determined by the method discussed in “In VitroRemoval of Stain with Dentifrice,” G. K. Stookey, et al., J. DentalRes., 61, 1236-9, 1982. RDA values are typically determined according tothe method set forth by Hefferren, Journal of Dental Research,July-August 1976, pp. 563-573, and described in Wason, U.S. Pat. Nos.4,340,583, 4,420,312, and 4,421,527. RDA values may also be determinedby the ADA recommended procedure for determination of dentifriceabrasivity.

Micrographs of commercially available precipitated silicas ZEODENT 109and ZEODENT 119, show irregularly shaped-agglomerated particles.Particles appear to be made of agglomerated smaller particles looselypacked together.

In some embodiments, the composition may comprise a gel network. In someembodiments, the composition may comprise one or more of the following:anticaries agent, antierosion agent, antibacterial agent, anticalculusagent, antihypersensitivity agent, anti-inflammatory agent, antiplaqueagent, antigingivitis agent, antimalodor agent, and/or an antistainagent. In some embodiments, the composition may comprise an additionalabrasive material, including, but not limited to untreated precipitatedsilica, calcium carbonate, dicalcium phosphate dihydrate, calciumphosphate, perlite, pumice, calcium pyrophosphate, nanodiamonds, othersurface treated and de-hydrated precipitated silica, fused silica andmixtures thereof. Some embodiments may be a method of cleaning subject'steeth and oral cavity by using an oral care composition comprising aheat treated precipitated silica abrasive in an orally acceptablecarrier.

Compositions may comprise additional anti-sensitivity agents such as,for example, tubule blocking agents and/or desensitivity agents. Tubuleblocking agents may be selected from the group consisting of stannousion source, strontium ion source, calcium ion source, phosphorus ionsource, aluminum ion source, magnesium ion source, amino acids,bioglasses, nanoparticulates, polycarboxylates, Gantrez, and mixturesthereof. The amino acids may be basic amino acids, and a basic aminoacid may be arginine. Nanoparticulates may be selected from the groupconsisting of nanohydroxy apatite, nanotitanium dioxide, nano metaloxides, and mixtures thereof. The desensitivity agent may be a potassiumsalt selected from the group consisting of potassium fluoride, potassiumcitrate, potassium nitrate, potassium chloride, and mixtures thereof.Some embodiments may be a method of reducing hypersensitivity of theteeth by administering to a subject in need an oral care compositioncomprising a heat treated precipitated silica, wherein the heat treatedprecipitated silica has a median particle size of 0.25 micron to about5.0 microns.

In some embodiments, the particle size may be relatively large to bepart of a prophy paste or some other non-daily use paste. In suchembodiments, an additional abrasive may be used, selected from the groupconsisting of pumice, perlite, precipitated silica, calcium carbonate,rice hull silica, fused silica, silica gels, aluminas, phosphatesincluding orthophosphates, polymetaphosphates, pyrophosphates, otherinorganic particulates, and mixtures thereof.

Some embodiments may have a flavoring agent.

Precipitated, or hydrated, silicas may be made by dissolving silica(sand) using sodium hydroxide and precipitating by adding sulfuric acid.After washing and drying, the material is then milled Such precipitatedsilicas may be made by the process disclosed in U.S. Pat. No. 6,740,311,White, 2004. Precipitated and other silicas are described in more detailin the Handbook of Porous Solids, edited by Ferdi Schuth, Kenneth S. W.Sing and Jens Weitkamp, chapter 4.7.1.1.1, called Formation of SilicaSols, Gels, and Powders, and in Cosmetic Properties and Structure ofFine-Particle Synthetic Precipitated Silicas, S. K. Wason, Journal ofSoc. Cosmetic Chem., vol. 29, (1978), pp 497-521.

The amount of heat treated precipitated silica used in the presentinvention may be from about 1%, 2%, 5%, 7%, 10%, 12%, 15%, 20%, 25%,30%, 35%, 40%, 45%, 50% to about 5%, 7%, 10%, 12%, 15%, 20%, 25%, 30%,35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%, or any combination thereof.The heat treated precipitated silicas of the present invention may beused alone or with other abrasives. A composition may comprise more thanone type of heat treated precipitated silica. The total abrasive in thecompositions described herein is generally present at a level of fromabout 5% to about 70%, by weight of the composition. Preferably,dentifrice compositions contain from about 5% to about 50% of totalabrasive, by weight of the composition.

The heat treated precipitated silica may be used in combination withinorganic particulates that have been treated with non-ionic surfactantssuch as ethoxylated and non-ethoxylated fatty alcohols, acid and esters.One example of such non-ionic surfactant is PEG 40 hydrogenated Castoroil. In general, the oral care compositions of the present invention maybe used with additional abrasive material, such as one or more selectedfrom the group consisting of precipitated silica, calcium carbonate,rice hull silica, silica gels, aluminums, aluminum silicates, phosphatesincluding orthophosphates, polymetaphostphates, pyrophosphates, otherinorganic particulates, dicalcium phosphate dihydrate, calciumphosphate, perlite, pumice, calcium pyrophosphate, nanodiamonds, surfacetreated and de-hydrated precipitated silica, and mixtures thereof.

The heated treated precipitated silica particles of the presentinvention may be used in combination with other precipitated silicas,such as surface-modified precipitated silica, other dehydratedprecipitated silicas, or precipitated silicas with reduced porosity,reduced surface hydroxyl groups, or small surface areas that have bettercation compatibility vs. regular precipitated silicas. But it isemphasized that these particular precipitated silicas aresurface-treated in an attempt to reduce surface hydroxyls and to improveproperties such as low porosity or cationic compatibility, but that theywould still be considered precipitated silicas. (See, for example, U.S.Pat. No. 7,255,852, U.S. Pat. No. 7,438,895, WO 9323007, and WO9406868.) Other abrasive polishing materials may include silica gels,rice hull silica, aluminas, phosphates including orthophosphates,polymetaphosphates, and pyrophosphates, and mixtures thereof. Specificexamples include dicalcium orthophosphate dihydrate, calciumpyrophosphate, tricalcium phosphate, calcium polymetaphosphate,insoluble sodium polymetaphosphate, hydrated alumina, beta calciumpyrophosphate, calcium carbonate, and resinous abrasive materials suchas particulate condensation products of urea and formaldehyde, andothers such as disclosed by Cooley et al in U.S. Pat. No. 3,070,510,issued Dec. 25, 1962.

The abrasive can be silica gels such as the silica xerogels described inPader et al., U.S. Pat. No. 3,538,230, issued Mar. 2, 1970, andDiGiulio, U.S. Pat. No.t 3,862,307, issued Jan. 21, 1975. Examples arethe silica xerogels marketed under the trade name “Syloid” by the W. R.Grace & Company, Davison Chemical Division. Also there are theprecipitated silica materials such as those marketed by the J. M. HuberCorporation under the trade name, “ZEODENT”, particularly the silicascarrying the designation “ZEODENT 109” (Z-109) and “ZEODENT 119”(Z-119). Other precipitated silicas commercially available andcomparable to ZEODENT 109 and ZEODENT 119 include, for example, TIXOSIL63, TIXOSIL 73, and TIXOSIL 103, all made by Rhodia, Huber silicasZ-103, Z-113, and Z-124, OSC DA, made by OSC in Taiwan, and ABSIL-200and ABSIL-HC, made by Madhu Silica. Of these commercially availableprecipitated silicas, TIXOSIL 73 is the most similar to ZEODENT 119. Thepresent precipitated silica abrasives may be used in combination withheat treated precipitated silica and other abrasives.

The types of precipitated silica dental abrasives that may be mixed withthe heat treated precipitated silica of the present invention aredescribed in more detail in Wason, U.S. Pat. No. 4,340,583, issued Jul.29, 1982. Precipitated silica abrasives are also described in Rice, U.S.Pat. Nos. 5,589,160; 5,603,920; 5,651,958; 5,658,553; and 5,716,601.

Stannous Ion

The oral compositions of the present invention will include a stannousion source. As stated before, one of the advantages of heat treatedprecipitated silica is its compatibility with other materials,particularly materials that are reactive and can loose efficacy.Stannous ions are considered to be reactive so the use of stannous ionswith a heat treated precipitated silica may have some importantbenefits. Because heat treated precipitated silica does not react asmuch with stannous as compared to precipitated silica and othertraditional abrasives, less of the stannous can be used but resulting inthe same efficacy or even greater efficacy. It has been reported thatstannous may have potential aesthetic negatives such an unpleasant orstrong taste, astringency, staining, or other negative aesthetics thatmake the stannous containing oral compositions less desirable forconsumers. Therefore, using a lower amount of stannous may be preferred.Additionally, the use of less stannous for the same or similar efficacy(as a formula containing precipitated silica) is a cost savings and mayhave better aesthetics and less stain. Alternatively, if the same amountof stannous is used as traditionally used, the stannous would havehigher efficacy as more of it is available to provide the benefit.Because the heat treated precipitated silica is slightly harder thantraditional abrasives such as precipitated silica, the heat treatedprecipitated silica may also remove more stain and/or clean better. Ithas also been discovered that stannous containing formulations mayincrease the strength of the teeth. Therefore, formulations containingstannous may have lower RDA scores than comparable formulations notcontaining stannous. The lower RDA scores may provide for a better PCRto RDA ratio as the heat treated precipitated silica is a good cleaningabrasive and the stannous provides for stronger teeth. The synergyprovided with the combination of heat treated precipitated silica andstannous provides a highly efficacious, high cleaning formula forconsumers.

The synergies between heat treated precipitated silica and stannous ionscan provide many benefits in oral compositions for consumers. The lowBET surface area, low number of surface hydroxyl group, and low porosityof the heat treated precipitated silica make it a suitable abrasive forstannous containing compositions.

The stannous ions may be provided from stannous fluoride and/or otherstannous salts. Stannous fluoride has been found to help in thereduction of gingivitis, plaque, sensitivity, erosion, inflammation andin improved breath benefits. The stannous ions provided in a dentifricecomposition will provide efficacy to a subject using the dentifricecomposition. Although efficacy could include benefits other than thereduction in gingivitis, efficacy is defined as a noticeable amount ofreduction in in situ plaque metabolism. Formulations providing suchefficacy typically include stannous levels provided by stannous fluorideand/or other stannous salts ranging from about 50 ppm to about 15,000ppm stannous ions in the total composition. The stannous ion is presentin an amount of from about 1,000 ppm to about 10,000 ppm, in oneembodiment from about 3,000 ppm to about 7,500 ppm. Other stannous saltsinclude organic stannous carboxylates, such as stannous acetate,stannous gluconate, stannous oxalate, stannous malonate, stannouscitrate, stannous ethylene glycoxide, stannous formate, stannoussulfate, stannous lactate, stannous tartrate, and the like. Otherstannous ion sources include, stannous halides such as stannouschlorides, stannous bromide, stannous iodide and stannous chloridedihydride. In one embodiment the stannous ion source is stannousfluoride, in another embodiment stannous chloride dehydrate ortrihydrate, or stannous gluconate. The combined stannous salts may bepresent in an amount of from about 0.001% to about 11%, by weight of theoral care compositions. The stannous salts may, in one embodiment, bepresent in an amount of from about 0.01% to about 7%, in anotherembodiment from about 0.1% to about 5%, and in another embodiment fromabout 1.5% to about 3%, by weight of the oral care composition.

Orally-Acceptable Carrier

The carrier for the components of the present compositions may be anyorally-acceptable vehicle suitable for use in the oral cavity. Thecarrier may comprise suitable cosmetic and/or therapeutic actives. Suchactives include any material that is generally considered safe for usein the oral cavity and that provides changes to the overall appearanceand/or health of the oral cavity, including, but not limited to,anti-calculus agents, fluoride ion sources, stannous ion sources,whitening agents, anti-microbial, anti-malodor agents, anti-sensitivityagents, anti-erosion agents, anti-caries agents, anti-plaque agents,anti-inflammatory agents, nutrients, antioxidants, anti-viral agents,analgesic and anesthetic agents, H-2 antagonists, and mixtures thereof.When present, the level of cosmetic and/or therapeutic active in theoral care composition is, in one embodiment from about 0.001% to about90%, in another embodiment from about 0.01% to about 50%, and in anotherembodiment from about 0.1% to about 30%, by weight of the oral carecomposition.

Actives

One of the advantages of heat treated precipitated silica is itscompatibility with other materials, particularly materials that arereactive and can lose efficacy such as actives. Because heat treatedprecipitated silica does not react as much with actives as compared tountreated precipitated silica and other traditional abrasives, less ofthe active can be used with the same efficacy. If the active has anypotential aesthetic negatives such an unpleasant or strong taste,astringency, staining, or other negative aesthetic, the lower amount ofactive may be preferred. Additionally, the use of less active for thesame or similar efficacy is a cost savings. Alternatively, if the sameamount of active as used as traditionally used, the active would havehigher efficacy as more of it is available to provide the benefit.

Actives include but are not limited to antibacterial actives, antiplaqueagents, anticaries agents, antisensitivity agents, antierosion agents,oxidizing agents, anti-inflammatory agents, anticalculus agents,nutrients, antioxidants, analgesic agents, anesthetic agents, H-1 andH-2 antagonists, antiviral actives, and combinations thereof. A materialor ingredient may be categorized as more than one type of materials.Such as an antioxidant may also be an antiplaque and antibacterialactive. Examples of suitable actives include stannous fluoride, sodiumfluoride, essential oils, mono alkyl phosphates, hydrogen peroxide, CPC,chlorhexidine, Triclosan, and combinations thereof. The following is anon-limiting list of actives that may be used in the present invention.

Fluoride Ion

The present invention may comprise a safe and effective amount of afluoride compound. The fluoride ion may be present in an amountsufficient to give a fluoride ion concentration in the composition at25° C., and/or in one embodiment can be used at levels of from about0.0025% to about 5.0% by weight, in another embodiment from about 0.005%to about 2.0% by weight, to provide anticaries effectiveness. A widevariety of fluoride ion-yielding materials can be employed as sources ofsoluble fluoride in the present compositions. Examples of suitablefluoride ion-yielding materials are disclosed in U.S. Pat. Nos.3,535,421, and 3,678,154. Representative fluoride ion sources include:stannous fluoride, sodium fluoride, potassium fluoride, amine fluoride,sodium monofluorophosphate, zinc fluoride, and many others. In oneembodiment the dentifrice composition comprises stannous fluoride orsodium fluoride, as well as mixtures thereof.

The pH of the oral composition may be from about 3 to about 10. The pHis typically measured as a slurry pH by methods known in the industry.Depending upon the actives used in the oral composition, a different pHmay be desired.

Anticalculus Agent

Dentifrice compositions of the present invention may also comprise ananti-calculus agent, which in one embodiment may be present from about0.05% to about 50%, by weight of the oral care composition, in anotherembodiment is from about 0.05% to about 25%, and in another embodimentis from about 0.1% to about 15%. The anti-calculus agent may be selectedfrom the group consisting of polyphosphates (including pyrophosphates)and salts thereof; polyamino propane sulfonic acid (AMPS) and saltsthereof; polyolefin sulfonates and salts thereof; polyvinyl phosphatesand salts thereof; polyolefin phosphates and salts thereof;diphosphonates and salts thereof; phosphonoalkane carboxylic acid andsalts thereof; polyphosphonates and salts thereof; polyvinylphosphonates and salts thereof; polyolefin phosphonates and saltsthereof; polypeptides; and mixtures thereof; polycarboxylates and saltsthereof; carboxy-substituted polymers; and mixtures thereof. In oneembodiment, the polymeric polycarboxylates employed herein include thosedescribed in U.S. Pat. No. 5032386. An example of these polymers that iscommercially available is Gantrez from International Speciality Products(ISP). In one embodiment, the salts are alkali metal or ammonium salts.Polyphosphates are generally employed as their wholly or partiallyneutralized water-soluble alkali metal salts such as potassium, sodium,ammonium salts, and mixtures thereof. The inorganic polyphosphate saltsinclude alkali metal (e.g. sodium) tripolyphosphate, tetrapolyphosphate,dialkyl metal (e.g. disodium) diacid, trialkyl metal (e.g. trisodium)monoacid, potassium hydrogen phosphate, sodium hydrogen phosphate, andalkali metal (e.g. sodium) hexametaphosphate, and mixtures thereof.Polyphosphates larger than tetrapolyphosphate usually occur as amorphousglassy materials. In one embodiment the polyphosphates are thosemanufactured by FMC Corporation, which are commercially known asSodaphos (n≈6), Hexaphos (n≈13), and Glass H (n≈21, sodiumhexametaphosphate), and mixtures thereof. The pyrophosphate salts usefulin the present invention include, alkali metal pyrophosphates, di-,tri-, and mono-potassium or sodium pyrophosphates, dialkali metalpyrophosphate salts, tetraalkali metal pyrophosphate salts, and mixturesthereof. In one embodiment the pyrophosphate salt is selected from thegroup consisting of trisodium pyrophosphate, disodium dihydrogenpyrophosphate (Na₂H₂P₂O₇), dipotassium pyrophosphate, tetrasodiumpyrophosphate (Na₄P₂O₇), tetrapotassium pyrophosphate (K₄P₂O₇), andmixtures thereof. Polyolefin sulfonates include those wherein the olefingroup contains 2 or more carbon atoms, and salts thereof. Polyolefinphosphonates include those wherein the olefin group contains 2 or morecarbon atoms. Polyvinylphosphonates include polyvinylphosphonic acid.Diphosphonates and salts thereof include azocycloalkane-2,2-diphosphonicacids and salts thereof, ions of azocycloalkane-2,2-diphosphonic acidsand salts thereof, azacyclohexane-2,2-diphosphonic acid,azacyclopentane-2,2-diphosphonic acid,N-methyl-azacyclopentane-2,3-diphosphonic acid, EHDP(ethane-1-hydroxy-1,1,-diphosphonic acid), AHP(azacycloheptane-2,2-diphosphonic acid),ethane-1-amino-1,1-diphosphonate, dichloromethane-diphosphonate, etc.Phosphonoalkane carboxylic acid or their alkali metal salts include PPTA(phosphonopropane tricarboxylic acid), PBTA(phosphonobutane-1,2,4-tricarboxylic acid), each as acid or alkali metalsalts. Polyolefin phosphates include those wherein the olefin groupcontains 2 or more carbon atoms. Polypeptides include polyaspartic andpolyglutamic acids.

Whitening Agent

A whitening agent may be included as an active in the present dentifricecompositions. The actives suitable for whitening are selected from thegroup consisting of alkali metal and alkaline earth metal peroxides,metal chlorites, perborates inclusive of mono and tetrahydrates,perphoshates, percarbonates, peroxyacids, and persulfates, such asammonium, potassium, sodium and lithium persulfates, and combinationsthereof. Suitable peroxide compounds include hydrogen peroxide, ureaperoxide, calcium peroxide, carbamide peroxide, magnesium peroxide, zincperoxide, strontium peroxide and mixtures thereof. In one embodiment theperoxide compound is carbamide peroxide. Suitable metal chloritesinclude calcium chlorite, barium chlorite, magnesium chlorite, lithiumchlorite, sodium chlorite, and potassium chlorite. Additional whiteningactives may be hypochlorite and chlorine dioxide. In one embodiment thechlorite is sodium chlorite. In another embodiment the percarbonate issodium percarbonate. In one embodiment the persulfates are oxones. Thelevel of these substances is dependent on the available oxygen orchlorine, respectively, that the molecule is capable of providing tobleach the stain. In one embodiment the whitening agents may be presentat levels from about 0.01% to about 40%, in another embodiment fromabout 0.1% to about 20%, in another embodiment form about 0.5% to about10%, and in another embodiment from about 4% to about 7%, by weight ofthe oral care composition.

Oxidizing Agent

The compositions of the invention may contain an oxidizing agent, suchas a peroxide source. A peroxide source may comprise hydrogen peroxide,calcium peroxide, carbamide peroxide, or mixtures thereof. In someembodiments, the peroxide source is hydrogen peroxide. Other peroxideactives can include those that produce hydrogen peroxide when mixed withwater, such as percarbonates, e.g., sodium percarbonates. In certainembodiments, the peroxide source may be in the same phase as a stannousion source. In some embodiments, the composition comprises from about0.01% to about 20% of a peroxide source, in other embodiments from about0.1% to about 5%, in certain embodiments from about 0.2% to about 3%,and in another embodiment from about 0.3% to about 2.0% of a peroxidesource, by weight of the oral composition. The peroxide source may beprovided as free ions, salts, complexed, or encapsulated. It isdesirable that the peroxide in the composition is stable. The peroxidemay provide a reduction in staining, as measured by the Cycling StainTest, or other relevant methods.

In addition to the optional ingredients detailed below, certainthickeners and flavors offer better compatibility with oxidizing agentssuch as peroxide. For example, in some embodiments, preferred thickeningagents may be cross-linked polyvinylpyrrolidone, polyacrylates,alkylated polyacrylates, alkylated cross-linked polyacrylates, polymericalkylated polyethers, carbomers, alkylated carbomers, gel networks,non-ionic polymeric thickeners, Sepinov EMT 10 (Seppic-hydroxyethylacrylate/sodium acryloldimethyltaurate copolymer), Pure Thix 1450, 1442,HH (PEG 180 laureth-50/TMMP or Polyether 1-Rockwood Specialties),Structure 2001 (Akzo-Acrylates/Steareth-20 Itaconate copolymer),Structure 3001 (Akzo-Acrylates/Ceteth-20 Itaconate copolymer), Aculyn 28(Dow Chemical/Rohm and Haas-Acrylates/Beheneth-25 MethacrylateCopolymer), Genopur 3500D (Clariant), Aculyn 33 (Dow Chemical/Rohm andHaas-Acrylates Copolymer), Aculyn 22 (Dow Chemical/Rohm andHaas-Acrylates/Steareth-20 Methacrylate Copolymer), Aculyn 46 (DowChemical/Rohm and Haas-PEG-150/Stearyl Alcohol/SMDI Copolymer), A500(crosslinked carboxymethylcellulose-Hercules), Structure XL(hydroxypropyl starch phosphate-National Starch), and mixtures thereof.

Other suitable thickening agents may include polymeric sulfonic acidssuch as Aristoflex AVC, AVS, BLV and HMB (Clariant,acryloyldimethyltaurate polymers, co-polymers and cross polymers),Diaformer (Clariant, amineoxide methacrylate copolymer), Genapol(Clariant, fatty alcohol polyglycol ether and alkylated polyglycolethoxylated fatty alcohol), fatty alcohols, ethoxylated fatty alcohols,high molecular weight non-ionic surfactants such as BRIJ 721 (Croda),and mixtures thereof.

Suitable flavor systems particularly compatible with peroxide includethose discussed in US application 2007/0231278. In one embodiment, theflavor system comprises menthol in combination with at least onesecondary cooling agent along with selected traditional flavorcomponents that have been found to be relatively stable in the presenceof peroxide. By “stable” herein is meant that the flavor character orprofile does not significantly change or is consistent during the lifeof the product.

The present composition may comprise from about 0.04% to 1.5% totalcoolants (menthol+secondary coolant) with at least about 0.015% mentholby weight. Typically, the level of menthol in the final compositionranges from about 0.015% to about 1.0% and the level of secondarycoolant(s) ranges from about 0.01% to about 0.5%. Preferably, the levelof total coolants ranges from about 0.03% to about 0.6%.

Suitable secondary cooling agents or coolants to be used with mentholinclude a wide variety of materials such as carboxamides, ketals, diols,menthyl esters and mixtures thereof. Examples of secondary coolants inthe present compositions are the paramenthan carboxamide agents such asN-ethyl-p-menthan-3-carboxamide, known commercially as “WS-3”,N,2,3-trimethyl-2-isopropylbutanamide, known as “WS-23”, and others inthe series such as WS-5, WS-11, WS-14 and WS-30. Additional suitablecoolants include 3-1-menthoxypropane-1,2-diol known as TK-10manufactured by Takasago; menthone glycerol acetal known as MGA; menthylesthers such as menthyl acetate, menthyl acetoacetate, menthyl lactateknown as Frescolat® supplied by Haarmann and Reimer, and monomenthylsuccinate under the tradename Physcool from V. Mane. The terms mentholand menthyl as used herein include dextro- and levorotatory isomers ofthese compounds and racemic mixtures thereof. TK-10 is described in U.S.Pat. No. 4,459,425, Amano et al., issued July 10, 1984. WS-3 and otheragents are described in U.S. Pat. No. 4,136,163, Watson, et al., issuedJan. 23, 1979.

Flavoring agents are generally used in the compositions at levels offrom about 0.001% to about 5%, by weight of the composition.

Antibacterial Agent

Antimicrobial agents may be included in the dentifrice compositions ofthe present invention. Such agents may include, but are not limited tocationic antibacterials, such as chlorhexidine, alexidine, hexetidine,benzalkonium chloride, domiphen bromide, cetylpyridinium chloride (CPC),tetradecylpyridinium chloride (TPC), N-tetradecyl-4-ethylpyridiniumchloride (TDEPC), octenidine, bisbiguanides, zinc or stannous ionagents, grapefruit extract, and mixtures thereof. Other antibacterialand antimicrobial agents include, but are not limited to:5-chloro-2-(2,4-dichlorophenoxy)-phenol, commonly referred to astriclosan; 8-hydroxyquinoline and its salts, copper II compounds,including, but not limited to, copper(II) chloride, copper(II) sulfate,copper(II) acetate, copper(II) fluoride and copper(II) hydroxide;phthalic acid and its salts including, but not limited to thosedisclosed in U.S. Pat. 4,994,262, including magnesium monopotassiumphthalate; sanguinarine; salicylanilide; iodine; sulfonamides;phenolics; delmopinol, octapinol, and other piperidino derivatives;niacin preparations; nystatin; apple extract; thyme oil; thymol;antibiotics such as augmentin, amoxicillin, tetracycline, doxycycline,minocycline, metronidazole, neomycin, kanamycin, cetylpyridiniumchloride, and clindamycin; analogs and salts of the above; methylsalicylate; hydrogen peroxide; metal salts of chlorite; pyrrolidoneethyl cocoyl arginate; lauroyl ethyl arginate monochlorohydrate; andmixtures of all of the above. In another embodiment, the compositioncomprises phenolic antimicrobial compounds and mixtures thereof.Antimicrobial components may be present from about 0.001% to about 20%by weight of the oral care composition. In another embodiment theantimicrobial agents generally comprise from about 0.1% to about 5% byweight of the oral care compositions of the present invention.

Other antimicrobial agents may be, but are not limited to, essentialoils. Essential oils are volatile aromatic oils which may be syntheticor may be derived from plants by distillation, expression or extraction,and which usually carry the odor or flavor of the plant from which theyare obtained. Useful essential oils may provide antiseptic activity.Some of these essential oils also act as flavoring agents. Usefulessential oils include but are not limited to citra, thymol, menthol,methyl salicylate (wintergreen oil), eucalyptol, carvacrol, camphor,anethole, carvone, eugenol, isoeugenol, limonene, osimen, n-decylalcohol, citronel, a-salpineol, methyl acetate, citronellyl acetate,methyl eugenol, cineol, linalool, ethyl linalaol, safrola vanillin,spearmint oil, peppermint oil, lemon oil, orange oil, sage oil, rosemaryoil, cinnamon oil, pimento oil, laurel oil, cedar leaf oil, gerianol,verbenone, anise oil, bay oil, benzaldehyde, bergamot oil, bitteralmond, chiorothymol, cinnamic aldehyde, citronella oil, clove oil, coaltar, eucalyptus oil, guaiacol, tropolone derivatives such as hinokitiol,avender oil, mustard oil, phenol, phenyl salicylate, pine oil, pineneedle oil, sassafras oil, spike lavender oil, storax, thyme oil, tolubalsam, terpentine oil, clove oil, and combinations thereof. In oneembodiment the essential oils are selected from thymol, methylsalicylate, eucalyptol, menthol and combinations thereof.

Anti-Plaque Agent

The dentifrice compositions of the present invention may include ananti-plaque agent such as stannous salts, copper salts, strontium salts,magnesium salts, copolymers of carboxylated polymers such as Gantrez ora dimethicone copolyol. The dimethicone copolyol is selected from C12 toC20 alkyl dimethicone copolyols and mixtures thereof. In one embodimentthe dimethicone copolyol is cetyl dimethicone copolyol marketed underthe Trade Name Abil EM90. The dimethicone copolyol in one embodiment canbe present in a level of from about 0.001% to about 25%, in anotherembodiment from about 0.01% to about 5%, and in another embodiment fromabout 0.1% to about 1.5% by weight of the oral care composition.

Anti-Inflammatory Agent

Anti-inflammatory agents can also be present in the dentifricecompositions of the present invention. Such agents may include, but arenot limited to, non-steroidal anti-inflammatory (NSAID) agents oxicams,salicylates, propionic acids, acetic acids and fenamates. Such NSAIDsinclude but are not limited to ketorolac, flurbiprofen, ibuprofen,naproxen, indomethacin, diclofenac, etodolac, indomethacin, sulindac,tolmetin, ketoprofen, fenoprofen, piroxicam, nabumetone, aspirin,diflunisal, meclofenamate, mefenamic acid, oxyphenbutazone,phenylbutazone and acetaminophen. Use of NSAIDs such as ketorolac areclaimed in U.S. Pat. No. 5,626,838. Disclosed therein are methods ofpreventing and/or treating primary and reoccurring squamous cellcarcinoma of the oral cavity or oropharynx by topical administration tothe oral cavity or oropharynx of an effective amount of an NSAID.Suitable steroidal anti-inflammatory agents include corticosteroids,such as fluccinolone, and hydrocortisone.

Nutrients

Nutrients may improve the condition of the oral cavity and can beincluded in the dentifrice compositions of the present invention.Nutrients include minerals, vitamins, oral nutritional supplements,enteral nutritional supplements, and mixtures thereof. Useful mineralsinclude calcium, phosphorus, zinc, manganese, potassium and mixturesthereof. Vitamins can be included with minerals or used independently.Suitable vitamins include Vitamins C and D, thiamine, riboflavin,calcium pantothenate, niacin, folic acid, nicotinamide, pyridoxine,cyanocobalamin, para-aminobenzoic acid, bioflavonoids, and mixturesthereof. Oral nutritional supplements include amino acids, lipotropics,fish oil, and mixtures thereof. Amino acids include, but are not limitedto L-Tryptophan, L-Lysine, Methionine, Threonine, Levocarnitine orL-carnitine and mixtures thereof. Lipotropics include, but are notlimited to, choline, inositol, betaine, linoleic acid, linolenic acid,and mixtures thereof. Fish oil contains large amounts of Omega-3 (N-3)polyunsaturated fatty acids, eicosapentaenoic acid and docosahexaenoicacid. Enteral nutritional supplements include, but are not limited to,protein products, glucose polymers, corn oil, safflower oil, mediumchain triglycerides. Minerals, vitamins, oral nutritional supplementsand enteral nutritional supplements are described in more detail in DrugFacts and Comparisons (loose leaf drug information service), WoltersKluer Company, St. Louis, Mo., ©1997, pps. 3-17 and 54-57.

Antioxidants

Antioxidants are generally recognized as useful in dentifricecompositions. Antioxidants are disclosed in texts such as Cadenas andPacker, The Handbook of Antioxidants, ©1996 by Marcel Dekker, Inc.Antioxidants useful in the present invention include, but are notlimited to, Vitamin E, ascorbic acid, Uric acid, carotenoids, Vitamin A,flavonoids and polyphenols, herbal antioxidants, melatonin,aminoindoles, lipoic acids and mixtures thereof.

Analgesic and Anesthetic Agents

Anti-pain or desensitizing agents can also be present in the dentifricecompositions of the present invention. Analgesics are agents thatrelieve pain by acting centrally to elevate pain threshold withoutdisturbing consciousness or altering other sensory modalities. Suchagents may include, but are not limited to: strontium chloride;potassium nitrate; sodium fluoride; sodium nitrate; acetanilide;phenacetin; acertophan; thiorphan; spiradoline; aspirin; codeine;thebaine; levorphenol; hydromorphone; oxymorphone; phenazocine;fentanyl; buprenorphine; butaphanol; nalbuphine; pentazocine; naturalherbs, such as gall nut; Asarum; Cubebin; Galanga; scutellaria;Liangmianzhen; and Baizhi Anesthetic agents, or topical analgesics, suchas acetaminophen, sodium salicylate, trolamine salicylate, lidocaine andbenzocaine may also be present. These analgesic actives are described indetail in Kirk-Othmer, Encyclopedia of Chemical Technology, FourthEdition, Volume 2, Wiley-Interscience Publishers (1992), pp. 729-737.

H-1 and H-2 Antagonists and Antiviral Actives

The present invention may also optionally comprise selective H-1 and H-2antagonists including compounds disclosed in U.S. Pat. No. 5,294,433.Antiviral actives useful in the present composition include any knowactives that are routinely use to treat viral infections. Suchanti-viral actives are disclosed in Drug Facts and Comparisons, WoltersKluer Company, ©1997, pp. 402(a)-407(z). Specific examples includeanti-viral actives disclosed in U.S. Pat. No. 5,747,070, issued May 5,1998. Said Patent discloses the use of stannous salts to controlviruses. Stannous salts and other anti-viral actives are described indetail in Kirk & Othmer, Encyclopedia of Chemical Technology, ThirdEdition, Volume 23, Wiley-lnterscience Publishers (1982), pp. 42-71. Thestannous salts that may be used in the present invention would includeorganic stannous carboxylates and inorganic stannous halides. Whilestannous fluoride may be used, it is typically used only in combinationwith another stannous halide or one or more stannous carboxylates oranother therapeutic agent.

Chelating Agent

The present compositions may optionally contain chelating agents, alsocalled chelants or sequestrants, many of which also have anticalculusactivity or tooth substantive activity. Use of chelating agents in oralcare products is advantageous for their ability to complex calcium suchas found in the cell walls of bacteria. Chelating agents can alsodisrupt plaque by removing calcium from the calcium bridges which helphold this biomass intact. Chelating agents also have the ability tocomplex with metallic ions and thus aid in preventing their adverseeffects on the stability or appearance of products. Chelation of ions,such as iron or copper, helps retard oxidative deterioration of finishedproducts.

In addition, chelants can in principle remove stains by binding to teethsurfaces thereby displacing color bodies or chromagens. The retention ofthese chelants can also prevent stains from accruing due to disruptionof binding sites of color bodies on tooth surfaces.

Chelants may be desired to be added to formulations containing cationicantibicaterial agents. It may be desired to add chelants to stannouscontaining formulations. The chelant is able to help stabilize thestannous and keep a higher amount of the stannous availible. The chelantmay be used in stannous formulations which have a pH above about 4.0. Insome formulations, the stannous may be stable without the need for achelant as the stannous is more stable with heat treated precipitatedsilica as compared to precipitated silica.

Suitable chelating agents include soluble phosphate compounds, such asphytates and linear polyphosphates having two or more phosphate groups,including tripolyphosphate, tetrapolyphosphate and hexametaphosphate,among others. Preferred polyphosphates are those having the number ofphosphate groups n averaging from about 6 to about 21, such as thosecommercially known as Sodaphos (n≈6), Hexaphos (n≈13), and Glass H(n≈21). Other polyphosphorylated compounds may be used in addition to orinstead of the polyphosphate, in particular polyphosphorylated inositolcompounds such as phytic acid, myo-inositol pentakis(dihydrogenphosphate); myo-inositol tetrakis(dihydrogen phosphate), myo-inositoltrikis(dihydrogen phosphate), and an alkali metal, alkaline earth metalor ammonium salt thereof. Preferred herein is phytic acid, also known asmyo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) or inositolhexaphosphoric acid, and its alkali metal, alkaline earth metal orammonium salts. Herein, the term “phytate” includes phytic acid and itssalts as well as the other polyphosphorylated inositol compounds. Theamount of chelating agent in the compositions will depend on thechelating agent used and typically will be from at least about 0.1% toabout 20%, preferably from about 0.5% to about 10% and more preferablyfrom about 1.0% to about 7%.

Still other phosphate compounds that are useful herein for their abilityto bind, solubilize and transport calcium are the surface activeorganophosphate compounds described above useful as tooth substantiveagents including organic phosphate mono-, di- or triesters.

Other suitable agents with chelating properties for use in controllingplaque, calculus and stain include polyphosphonates described in U.S.Pat. No. 3,678,154 to Widder et al., U.S. Pat. No. 5,338,537 to White,Jr., and U.S. Pat. No. 5,451, to Zerby et al.; carbonyl diphosphonatesin U.S. Pat. No. 3,737,533 to Francis; acrylic acid polymer or copolymerin U.S. Pat. No. 4,847,070, Jul. 11, 1989 to Pyrz et al. and in U.S.Pat. No. 4,661,341, Apr. 28, 1987 to Benedict et al.; sodium alginate inU.S. Pat. No. 4,775,525, issued Oct. 4, 1988, to Pera; polyvinylpyrrolidone in GB 741,315, WO 99/12517 and U.S. Pat. Nos. 5,538,714 toPink et al.; and copolymers of vinyl pyrrolidone with carboxylates inU.S. Pat. Nos. 5,670,138 to Venema et al. and in JP Publication No.2000-0633250 to Lion Corporation.

Still other chelating agents suitable for use in the present inventionare the anionic polymeric polycarboxylates. Such materials are wellknown in the art, being employed in the form of their free acids orpartially or preferably fully neutralized water soluble alkali metal(e.g. potassium and preferably sodium) or ammonium salts. Examples are1:4 to 4:1 copolymers of maleic anhydride or acid with anotherpolymerizable ethylenically unsaturated monomer, preferably methyl vinylether (methoxyethylene) having a molecular weight (M.W.) of about 30,000to about 1,000,000. These copolymers are available for example asGantrez® AN 139 (M.W. 500,000), AN 119 (M.W. 250,000) and S-97Pharmaceutical Grade (M.W. 70,000), of GAF Chemicals Corporation.

Other operative polymeric polycarboxylates include the 1:1 copolymers ofmaleic anhydride with ethyl acrylate, hydroxyethyl methacrylate,N-vinyl-2-pyrrolidone, or ethylene, the latter being available forexample as Monsanto EMA No. 1103, M.W. 10,000 and EMA Grade 61, and 1:1copolymers of acrylic acid with methyl or hydroxyethyl methacrylate,methyl or ethyl acrylate, isobutyl vinyl ether or N-vinyl-2-pyrrolidone.

Additional operative polymeric polycarboxylates are disclosed in U.S.Pat. No. 4,138,477, Feb. 6, 1979 to Gaffar and U.S. Pat. No. 4,183,914,Jan. 15, 1980 to Gaffar et al. and include copolymers of maleicanhydride with styrene, isobutylene or ethyl vinyl ether; polyacrylic,polyitaconic and polymaleic acids; and sulfoacrylic oligomers of M.W. aslow as 1,000 available as Uniroyal ND-2.

Other suitable chelants include polycarboxylic acids and salts thereofdescribed in U.S. Pat. No. 5,015,467 to Smitherman U.S. Pat. No.5,849,271 and U.S. Pat. No. 5,622,689 both to Lukacovic; such astartaric acid, citric acid, gluconic acid, malic acid; succinic acid,disuccinic acid and salts thereof, such as sodium or potassium gluconateand citrate; citric acid/alkali metal citrate combination; disodiumtartrate; dipotassium tartrate; sodium potassium tartrate; sodiumhydrogen tartrate; potassium hydrogen tartrate; acid or salt form ofsodium tartrate monosuccinate, potassium tartrate disuccinate, andmixtures thereof. In some embodiments, there may be mixtures orcombinations of chelating agents.

Tooth Substantive Agent

The present invention may include a tooth substantive agent. Forpurposes of this application, tooth substantive agents are included aschelants also. Suitable agents may be polymeric surface active agents(PMSA's), including polyelectrolytes, more specifically anionicpolymers. The PMSA's contain anionic groups, e.g., phosphate,phosphonate, carboxy, or mixtures thereof, and thus, have the capabilityto interact with cationic or positively charged entities. The “mineral”descriptor is intended to convey that the surface activity orsubstantivity of the polymer is toward mineral surfaces such as calciumphosphate minerals in teeth.

PMSA's are useful in the present compositions because of their manybenefits such as stain prevention. The PMSA's include any agent whichwill have a strong affinity for the tooth surface, deposit a polymerlayer or coating on the tooth surface and produce the desired surfacemodification effects. Suitable examples of such polymers arepolyelectrolytes such as condensed phosphorylated polymers;polyphosphonates; copolymers of phosphate- or phosphonate-containingmonomers or polymers with other monomers such as ethylenic allyunsaturated monomers and amino acids or with other polymers such asproteins, polypeptides, polysaccharides, poly(acrylate),poly(acrylamide), poly(methacrylate), poly(ethacrylate),poly(hydroxyalkylmethacrylate), poly(vinyl alcohol), poly(maleicanhydride), poly(maleate) poly(amide), poly(ethylene amine),poly(ethylene glycol), poly(propylene glycol), poly(vinyl acetate) andpoly(vinyl benzyl chloride); polycarboxylates and carboxy-substitutedpolymers; and mixtures thereof. Suitable polymeric mineral surfaceactive agents include the carboxy-substituted alcohol polymers describedin U.S. Pat. Nos. 5,292,501; 5,213,789, 5,093,170; 5,009,882; and4,939,284; all to Degenhardt et al. and the diphosphonate-derivatizedpolymers in U.S. Pat. No. 5,011,913 to Benedict et al; the syntheticanionic polymers including polyacrylates and copolymers of maleicanhydride or acid and methyl vinyl ether (e.g., Gantrez®), as described,for example, in U.S. Pat. No. 4,627,977, to Gaffar et al. A preferredpolymer is diphosphonate modified polyacrylic acid. Polymers withactivity must have sufficient surface binding propensity to desorbpellicle proteins and remain affixed to enamel surfaces. For toothsurfaces, polymers with end or side chain phosphate or phosphonatefunctions are preferred although other polymers with mineral bindingactivity may prove effective depending upon adsorption affinity.

One preferred PMSA is a polyphosphate. A polyphosphate is generallyunderstood to consist of two or more phosphate molecules arrangedprimarily in a linear configuration, although some cyclic derivativesmay be present. Although pyrophosphates (n=2) are technicallypolyphosphates, the polyphosphates desired are those having around threeor more phosphate groups so that surface adsorption at effectiveconcentrations produces sufficient non-bound phosphate functions, whichenhance the anionic surface charge as well as hydrophilic character ofthe surfaces. The inorganic polyphosphate salts desired includetripolyphosphate, tetrapolyphosphate and hexametaphosphate, amongothers. Polyphosphates larger than tetrapolyphosphate usually occur asamorphous glassy materials. Preferred in the present compositions arethe linear polyphosphates having the formula:

XO(XPO₃)_(n)X

wherein X is sodium, potassium or ammonium and n averages from about 3to about 125. Preferred polyphosphates are those having n averaging fromabout 6 to about 21, such as those commercially known as Sodaphos (n≈6),Hexaphos (n≈13), and Glass H (n≈21) and manufactured by FMC Corporationand Astaris. These polyphosphates may be used alone or in combination.Polyphosphates are susceptible to hydrolysis in high water formulationsat acid pH, particularly below pH 5. Thus it is preferred to uselonger-chain polyphosphates, in particular Glass H with an average chainlength of about 21. It is believed such longer-chain polyphosphates whenundergoing hydrolysis produce shorter-chain polyphosphates which arestill effective to deposit onto teeth and provide a stain preventivebenefit.

Also useful as tooth substantive agents are nonpolymeric phosphatecompounds, in particular polyphosphorylated inositol compounds such asphytic acid, myo-inositol pentakis(dihydrogen phosphate); myo-inositoltetrakis(dihydrogen phosphate), myo-inositol trikis(dihydrogenphosphate), and an alkali metal, alkaline earth metal or ammonium saltthereof. Preferred herein is phytic acid, also known as myo-inositol1,2,3,4,5,6-hexakis (dihydrogen phosphate) or inositol hexaphosphoricacid, and its alkali metal, alkaline earth metal or ammonium salts.Herein, the term “phytate” includes phytic acid and its salts as well asthe other polyphosphorylated inositol compounds.

Other surface active phosphate compounds useful as tooth substantiveagents include organophosphates such as phosphate mono-, di- ortriesters such as described in commonly assigned application publishedas US20080247973A1. Examples include mono-di- and tri-alkyl and alkyl(poly)alkoxy phosphates such as dodecyl phosphate, lauryl phosphate;laureth-1 phosphate; laureth-3 phosphate; laureth-9 phosphate;dilaureth-10 phosphate; trilaureth-4 phosphate; C12-18 PEG-9 phosphateand salts thereof. Many are commercially available from suppliersincluding Croda; Rhodia; Nikkol Chemical; Sunjin; Alzo; HuntsmanChemical; Clariant and Cognis. Some preferred agents are polymeric, forexample those containing repeating alkoxy groups as the polymericportion, in particular 3 or more ethoxy, propoxy isopropoxy or butoxygroups.

Additional suitable polymeric organophosphate agents include dextranphosphate, polyglucoside phosphate, alkyl polyglucoside phosphate,polyglyceryl phosphate, alkyl polyglyceryl phosphate, polyetherphosphates and alkoxylated polyol phosphates. Some specific examples arePEG phosphate, PPG phosphate, alkyl PPG phosphate, PEG/PPG phosphate,alkyl PEG/PPG phosphate, PEG/PPG/PEG phosphate, dipropylene glycolphosphate, PEG glyceryl phosphate, PBG (polybutylene glycol) phosphate,PEG cyclodextrin phosphate, PEG sorbitan phosphate, PEG alkyl sorbitanphosphate, and PEG methyl glucoside phosphate.

Additional suitable non-polymeric phosphates include alkyl monoglyceride phosphate, alkyl sorbitan phosphate, alkyl methyl glucosidephosphate, alkyl sucrose phosphates.

Other useful tooth substantive agents include siloxane polymersfunctionalized with carboxylic acid groups, such as disclosed indisclosed in U.S. Pat. Nos. 7,025,950 and 7,166,235 both assigned to TheProcter & Gamble Co. These polymers comprise a hydrophobic siloxanebackbone and pendant anionic moieties containing carboxy groups and havethe ability to deposit onto surfaces from aqueous-based formulations orfrom essentially non-aqueous based formulations, forming a substantiallyhydrophobic coating on the treated surface. The carboxy functionalizedsiloxane polymers are believed to attach themselves to polar surfacesand to form a coating thereon by electrostatic interaction, i.e.,complex formation between the pendant carboxy groups with calcium ionspresent in teeth. The carboxy groups thus serve to anchor the siloxanepolymer backbone onto a surface thereby modifying it to be hydrophobic,which then imparts a variety of end use benefits to that surface such asease of cleaning, stain removal and prevention, whitening, etc. Thecarboxy functionalized siloxane polymer further acts to enhancedeposition of active agents onto the surface and to improve retentionand efficacy of these actives on the treated surface.

Also useful as tooth substantive agents are water-soluble orwater-dispersible polymeric agents prepared by copolymerizing one or amixture of vinyl pyrrolidone (VP) monomers with one or a mixture ofalkenyl carboxylate (AC) monomers, specifically C2-C12 alkenyl esters ofsaturated straight- or branched-chain C1-C19 alkyl carboxylic acidsdescribed in commonly assigned U.S. Pat. No. 6,682,722. Examples includecopolymers of vinyl pyrrolidone with one or a mixture of vinyl acetate,vinyl propionate, or vinyl butyrate. Preferred polymers have an averagemolecular weight ranging from about 1,000 to about 1,000,000, preferablyfrom 10,000 to 200,000, even more preferably from 30,000 to 100,000.

The amount of tooth substantive agent will typically be from about 0.1%to about 35% by weight of the total oral composition. In dentifriceformulations, the amount is preferably from about 2% to about 30%, morepreferably from about 5% to about 25%, and most preferably from about 6%to about 20%. In mouthrinse compositions, the amount of toothsubstantive agent is preferably from about 0.1% to 5% and morepreferably from about 0.5% to about 3%.

Additional Actives

Additional actives suitable for use in the present invention mayinclude, but are not limited to, insulin, steroids, herbal and otherplant derived remedies. Additionally, anti-gingivitis or gum care agentsknown in the art may also be included. Components which impart a cleanfeel to the teeth may optionally be included. These components mayinclude, for example, baking soda or Glass-H. Also, it is recognizedthat in certain forms of therapy, combinations of these above-namedagents may be useful in order to obtain an optimal effect. Thus, forexample, an anti-microbial and an anti-inflammatory agent may becombined in a single dentifrice composition to provide combinedeffectiveness.

Optional agents to be used include such known materials as syntheticanionic polymers, including polyacrylates and copolymers of maleicanhydride or acid and methyl vinyl ether (e.g., Gantrez), as described,for example, in U.S. Pat. No. 4,627,977, as well as, e.g., polyaminopropoane sulfonic acid (AMPS), zinc citrate trihydrate, polyphosphates(e.g., tripolyphosphate; hexametaphosphate), diphosphonates (e.g., EHDP;AHP), polypeptides (such as polyaspartic and polyglutamic acids), andmixtures thereof. Additionally, the dentifrice composition can include apolymer carrier, such as those described in U.S. Pat. Nos. 6,682,722 and6,589,512 and U.S. application Ser. Nos. 10/424,640 and 10/430,617.

Other Optional Ingredients Buffering Agents

The dentifrice compositions may contain a buffering agent. Bufferingagents, as used herein, refer to agents that can be used to adjust thepH of the dentifrice compositions to a range of about pH 3.0 to about pH10. The buffering agents include alkali metal hydroxides, ammoniumhydroxide, organic ammonium compounds, carbonates, sesquicarbonates,borates, silicates, phosphates, imidazole, and mixtures thereof.Specific buffering agents include monosodium phosphate, trisodiumphosphate, sodium benzoate, benzoic acid, sodium hydroxide, potassiumhydroxide, alkali metal carbonate salts, sodium carbonate, imidazole,pyrophosphate salts, sodium gluconate, lactic acid, sodium lactate,citric acid, and sodium citrate. Buffering agents are used at a level offrom about 0.1% to about 30%, preferably from about 0.1% to about 10%,and more preferably from about 0.3% to about 3%, by weight of thedentifrice compositions.

Coloring Agent

Coloring agents may also be added to the present composition. Thecoloring agent may be in the form of an aqueous solution, preferably 1%coloring agent in a solution of water. Pigments, pealing agents, fillerpowders, talc, mica, magnesium carbonate, calcium carbonate, bismuthoxychloride, zinc oxide, and other materials capable of creating avisual change to the dentifrice compositions may also be used. Colorsolutions and other agents generally comprise from about 0.01% to about5%, by weight of the composition. Titanium dioxide may also be added tothe present composition. Titanium dioxide is a white powder which addsopacity to the compositions. Titanium dioxide generally comprises fromabout 0.25% to about 5%, by weight of the composition.

Flavoring Agent

Suitable flavoring components include oil of wintergreen, clove bud oil,menthol, anethole, methyl salicylate, eucalyptol, cassia, 1-menthylacetate, sage, eugenol, parsley oil, oxanone, alpha-irisone, marjoram,lemon, orange, propenyl guaethol, cinnamon, vanillin, ethyl vanillin,heliotropine, 4-cis-heptenal, diacetyl, methyl-para-tert-butyl phenylacetate, cranberry, chocolate, green tea, and mixtures thereof. Theessential oils may also be included as flavoring agents and aredescribed above in the discussion of antibacterial agents. Coolants mayalso be part of the flavor composition. Coolants suitable for thepresent compositions include the paramenthan carboxyamide agents such asN-ethyl-p-menthan-3-carboxamide (known commercially as WS-3, WS-23,WS-5), MGA, TK-10, Physcool, and mixtures thereof. Salivating agents,warming agents, numbing agents, and other optional materials can be usedto deliver a signal while the oral composition is being used. In someembodiments, the amount of flavoring agent present, by weight of thecomposition, may be about 10%, about 20%, or about 50% less thancomparable precipitated silica formulations while achieving the sameflavor impact.

A flavor composition is generally used in the oral care compositions atlevels of from about 0.001% to about 5%, by weight of the oral carecomposition. The flavor composition will preferably be present in anamount of from about 0.01% to about 4%, more preferably from about 0.1%to about 3%, and more preferably from about 0.5% to about 2% by weight.

Similarly, coolants may not be absorbed as much in the presentcompositions, meaning that the coolants may last longer, or may be usedin lesser amounts. Essential oils also may be absorbed less so that lessmay be used to achieve the same effectiveness. The heat treatedprecipitated silica may not attach to the taste receptor likeprecipitated silica does, meaning that the taste receptor may be moreaccessible to the flavoring agent.

Other aesthetic benefits may be apparent to users, such as a clean mouthexperience and an increased perception of sweetness or coolness, forexample. The improved slick, clean mouthfeel may contribute to a lesserperception of dry mouth, and well as the improved cleaning of the heattreated precipitated silica may help remove layers of muscin andincrease the perception of moisturization. Another consumer aestheticbenefit may be improved rinsing out of the mouth of the oralcomposition, due to the inert heat treated precipitated silica particlesnot clumping, but remaining dispersed while the user brushes. Yetanother potential benefit is improved foaming. Again, because the heattreated precipitated silica is less reactive than precipitated silica,surfactants are more available and improved foaming may result.

Some embodiments may comprise a TRPV1 activator, a transient receptorpotential vanilloid receptor 1 activator, which is a ligand-gated,non-selective cation channel preferentially expressed on small-diametersensory neurons and detects noxious as well as other substances. Byadding a TRPV1 activator to an oral care composition with an off tastingcomponent, the user of the composition may experience an improved tasteover an oral care composition without the TRPV1 activator. Thus, theTRPV1 activator works to off-set the bad taste associated with manycomponents used in oral care compositions. These activators may not onlyoff-set bad tastes, but may also reduce dryness perception, by limitingthe mouth's ability to perceive dryness. In one embodiment, the TRPV1activator comprises vanillyl butyl ether, zingerone, capsaicin,capsiate, shoagol, gingerol, piperine, or a combination thereof. In oneembodiment, a TRPV1 activator will be added in an amount of about0.0001% to about 0.25% by weight of the oral care composition.

Sweetener

Sweetening agents can be added to the compositions. These includesweeteners such as saccharin, dextrose, sucrose, lactose, xylitol,maltose, levulose, aspartame, sodium cyclamate, D-tryptophan,dihydrochalcones, acesulfame, sucralose, neotame, and mixtures thereof.Various coloring agents may also be incorporated in the presentinvention. Sweetening agents are generally used in oral compositions atlevels of from about 0.005% to about 5%, by weight of the composition.

Thickening Agents

Additional thickening agents, such as polymeric thickeners, may beutilized. Suitable thickening agents are carboxyvinyl polymers,carrageenan, hydroxyethyl cellulose, laponite and water soluble salts ofcellulose ethers such as sodium carboxymethylcellulose and sodiumcarboxymethyl hydroxyethyl cellulose. Natural gums such as gum karaya,xanthan gum, gum arabic, and gum tragacanth can also be used. Colloidalmagnesium aluminum silicate or finely divided silica can be used as partof the thickening agent to further improve texture. Other thickeners mayinclude alkylated polyacrylates, alkylated cross-linked polyacrylates,or gel networks. Thickening agents can include polymeric polyethercompounds, e.g., polyethylene or polypropylene oxide (M.W. 300 to1,000,000), capped with alkyl or acyl groups containing 1 to about 18carbon atoms.

A suitable class of thickening or gelling agents includes a class ofhomopolymers of acrylic acid crosslinked with an alkyl ether ofpentaerythritol or an alkyl ether of sucrose, or carbomers. Carbomersare commercially available from Lubrizol (Ohio, USA) as the CARBOPOL®series. Particularly the carbopols include CARBOPOL 934, 940, 941, 956,and mixtures thereof.

Copolymers of lactide and glycolide monomers, the copolymer having themolecular weight in the range of from about 1,000 to about 120,000(number average), are useful for delivery of actives into theperiodontal pockets or around the periodontal pockets as a “subgingivalgel carrier.” These polymers are described in U.S. Pat. Nos. 5,198,220;5,242,910; and 4,443,430.

Due to precipitated silica's interaction with other formulationcomponents, precipitated silica can affect the rheology of a compositionover time. Heat treated precipitated silica, however, due to its lack ofinteraction with other formulation components, has little impact onrheology. This means that oral care compositions formulated with heattreated precipitated silica are more stable over time, which, amongother things, can allow for better cleaning and better predictability.Thus, in some embodiments, thickening agents, combinations and amounts,may be very different from those of traditional dentifrices. In thepresent invention, thickening agents may be used in an amount from about0% to about 15%, or from about 0.01% to about 10%, or in anotherembodiment from about 0.1% to about 5%, by weight of the total oralcomposition.

In some embodiments of the present invention, the composition maycomprise a thickening agent selected from natural and synthetic sources.In some embodiments, the thickening agent may be selected from the groupconsisting of clay, laponite, and mixtures thereof. In some embodiments,the composition may further comprise a thickening agent selected fromthe group consisting of carboxyvinyl polymers, carrageenan, hydroxyethylcellulose, water soluble salts of cellulose ethers such as sodiumcarboxymethylcellulose, cross-linked carboxymethylcellulose, sodiumhydroxyethyl cellulose, cross-linked starch, natural gums such as gumkaraya, xanthan gum, gum arabic, and gum tragacanth, magnesium aluminumsilicate, silica, alkylated polyacrylates, alkylated cross linkedpolyacrylates, and mixtures thereof.

Other possible thickeners include carbomers, hydrophobically modifiedcarbomers, carboxymethyl cellulose, cetyl/stearyl alcohol, sodiumalginate, gellan gum, acylated gellan gum, sodium hydroxypropyl starchphosphate, microcrystalline cellulose, micro fibrous cellulose,crosslinked polyvinyl pyrrolidone, cetyl hydroxyethyl cellulose,crosslinked sodium acryloyl methyl propane sulfonic acid and copolymers,and mixtures thereof.

The viscosity of the composition at the time it is made may remain theviscosity of the composition, or, stated differently, the compositionmay have a stable viscosity. For the viscosity to be considered stable,typically the viscosity changes no more than about 5% after 30 days. Insome embodiments, the viscosity of the composition does not change bymore than about 5% after about 30 days, by more than about 10% afterabout 30 days, by more than about 20% after about 30 days, or by morethan about 50% after about 90 days. Because the problem of unstableviscosity over time is more pronounced in formulations with low wateramounts, in some embodiments, the compositions of the present inventionmay contain less than about 20% total water, or less than about 10%total water.

Gel Networks

A gel network can be used in the oral composition. The gel network canbe used to structure the oral composition or to aid in delivering anactive, flavor, or other reactive material. The gel network may be usedto structure, meaning to thicken or provide the desired rheology, forthe heat treated precipitated silica oral compositions by itself or incombination with another thickener or structuring agent. A gel networkcomposition has a rheology that may be advantageous for heat treatedprecipitated silica as heat treated precipitated silica is more densethan some other abrasives or materials in the oral composition. Becausethe heat treated precipitated silica is heavier or more dense, it mayfall or drop out of the composition or solution more easily than otherless dense materials. This may be when the composition is diluted withwater. For example, when a dentifrice is used for brushing, it isdiluted by water when in the mouth. The dilution rheology for adentifrice containing a gel network aiding in structuring the dentifricemay be higher than dentifrices structured with polymeric or more typicalthickening materials. A higher dilution rheology is beneficial inkeeping the heat treated precipitated silica suspended and allowing theheat treated precipitated silica to participate more fully in thecleaning process. If a material, such as the abrasive, is not suspendedor maintained in the composition once diluted, the cleaning efficacy,such as pellicle cleaning ratio, may decrease. Additionally, as more ofthe abrasive or heat treated precipitated silica is suspended, the oralcomposition may contain less abrasives overall since more of theabrasive is able to participate in the cleaning. FIG. 13 shows PCR andRDA data for compositions structured by gel networks compared tocompositions which are not structured by gel networks but thickened withtypical polymeric binders. As shown, the PCR score increases from 92.5to 127.56 and from 95.44 to 121.04 when a gel network is used in aformula containing 15% heat treated precipitated silica. This PCRincrease of greater than about 10%, about 15%, about 20%, or about 25%may be due to the gel networks ability to suspend more of the heattreated precipitated silica during cleaning. While the cleaning scoresincrease, the abrasion remains in acceptable ranges.

The oral compositions of the present invention may comprise a dispersedgel network. As used herein, the term “gel network” refers to a lamellaror vesicular solid crystalline phase which comprises at least one fattyamphiphile, at least one surfactant, and a solvent. The lamellar orvesicular phase comprises bi-layers made up of a first layer comprisingthe fatty amphiphile and the secondary surfactant and alternating with asecond layer comprising the solvent. For the lamellar crystalline phaseto form, the fatty amphiphile and secondary surfactant must be dispersedwithin the solvent. The term “solid crystalline”, as used herein, refersto the structure of the lamellar or vesicular phase which forms at atemperature below the chain melt temperature of the layer in the gelnetwork comprising the one or more fatty amphiphiles. The gel networkssuitable for use in the present invention are described in more detailin US 2008/0081023A1 which describes the materials, methods of making,and uses of the gel networks. Additionally, US 2009/0246151A1 alsodescribes gel networks and method of making the compositions containinggel networks.

The gel network in the oral composition can be used to structure theoral composition. The structuring provided by the gel network providesthe desired rheology or viscosity by thickening the oral composition.The structuring can be done without the need for polymeric thickeningagents, however, polymeric thickeners or other agents could be used inaddition to the gel network to structure the oral composition. Becausethe heat treated precipitated silica does not provide any or as muchthickening as a typical precipitated silica, the thickening of the oralcomposition may benefit more from a gel network used to structure theoral composition. The small or no effect that the heat treatedprecipitated silica has the viscosity or thickening of the oralcomposition also may provide the benefit of being able to formulate anoral composition with a gel network or other thickening system and thenbeing able to add as much heat treated precipitated silica as desiredwithout needing to readjust the level of thickening as would be requiredif the amount of precipitated silica was adjusted.

The gel network component of the present invention comprises at leastone fatty amphiphile. As used herein, “fatty amphiphile” refers to acompound having a hydrophobic tail group and a hydrophilic head groupwhich does not make the compound water soluble (immiscible), wherein thecompound also has a net neutral charge at the pH of the oralcomposition. The fatty amphiphile can be selected from the groupconsisting of fatty alcohols, alkoxylated fatty alcohols, fatty phenols,alkoxylated fatty phenols, fatty amides, alkyoxylated fatty amides,fatty amines, fatty alkylamidoalkylamines, fatty alkyoxyalted amines,fatty carbamates, fatty amine oxides, fatty acids, alkoxylated fattyacids, fatty diesters, fatty sorbitan esters, fatty sugar esters, methylglucoside esters, fatty glycol esters, mono, di- and tri-glycerides,polyglycerine fatty esters, alkyl glyceryl ethers, propylene glycolfatty acid esters, cholesterol, ceramides, fatty silicone waxes, fattyglucose amides, phospholipids, and combinations thereof. Suitable fattyamphiphiles include a combination of cetyl alcohol and stearyl alcohol.

The gel network also comprises a surfactant. One or more surfactants arecombined with the fatty amphiphile and oral carrier to form the gelnetwork of the present invention. The surfactant is typically watersoluble or miscible in the solvent or oral carrier. Suitable surfactantsinclude anionic, zwitterionic, amphoteric, cationic, and nonionicsurfactants. In one embodiment, anionic surfactants such as sodiumlauryl sulfate, are preferred. The surfactants may be a combination ofmore than one type of surfactants, such as an anionic and nonionicsurfactant. The gel network will likely also comprise solvents, such aswater or other suitable solvents. The solvent and the surfactanttogether contribute to the swelling of the fatty amphiphile. This, inturn, leads to the formation and the stability of the gel network. Inaddition to forming the gel network, the solvent can help to keep thedentifrice composition from hardening upon exposure to air and provide amoist feel in the mouth. The solvent, as used herein, refers to suitablesolvents which can be used in the place of or in combination with waterin the formation of the gel network of the present invention. Suitablesolvents for the present invention include water, edible polyhydricalcohols such as glycerin, diglycerin, triglycerin, sorbitol, xylitol,butylene glycol, erythritol, polyethylene glycol, propylene glycol, andcombinations thereof. Sorbitol, glycerin, water, and combinationsthereof are preferred solvents.

To form a gel network, the oral compositions may comprise fattyamphiphile in an amount from about 0.05% to about 30%, preferably fromabout 0.1% to about 20%, and more preferably from about 0.5% to about10%, by weight of the oral composition. The amount of fatty amphiphilewill be chosen based on the formation of the gel network and thecomposition of the oral formulation. For example, an oral compositioncontaining low amounts of water may require about 1% of a fattyamphiphile whereas an oral composition with higher amounts of water mayrequire 6% or more of a fatty amphiphile. The amount of surfactant andsolvent needed to form the gel network will also vary based on thematerials chosen, the function of the gel network, and amount of fattyamphiphile. The surfactant as part of gel network phase is typically inan amount from about 0.01% to about 15%, preferably from about 0.1% toabout 10%, and more preferably from about 0.3% to about 5%, by weight ofthe oral composition. In some embodiments, a diluted solution ofsurfactant in water is utilized. In one embodiment, the amount ofsurfactant is chosen based on the level of foaming desired in the oralcomposition and on the irritation caused by the surfactant. The solventmay be present in an amount suitable to achieve a gel network whencombined with fatty amphiphile and surfactant according to the presentinvention. The oral compositions may comprise at least about 0.05% of asolvent, by weight of the oral composition. The solvent may be presentin the oral composition in amount of from about 0.1% to about 99%, fromabout 0.5% to about 95%, and from about 1% to about 90%.

Humectant

A humectant can help to keep the dentifrice composition from hardeningupon exposure to air and provide a moist feel in the mouth. A humectantor additional solvent may be added to the oral carrier phase. Suitablehumectants for the present invention include water, edible polyhydricalcohols such as glycerin, sorbitol, xylitol, butylene glycol,polyethylene glycol, propylene glycol, and combinations thereof.Sorbitol, glycerin, water, and combinations thereof are preferredhumectants. The humectant may be present in an amount of from about 0.1%to about 99%, from about 0.5% to about 95%, and from about 1% to about90%.

Surfactants

A surfactant may be added to the dentifrice composition. Surfactants,also commonly referred to as sudsing agents, may aid in the cleaning orfoaming of the dentifrice composition. Suitable surfactants are thosewhich are reasonably stable and foam throughout a wide pH range. Thesurfactant may be anionic, nonionic, amphoteric, zwitterionic, cationic,or mixtures thereof.

Examples of anionic surfactants useful herein include the water-solublesalts of alkyl sulfates having from 8 to 20 carbon atoms in the alkylradical (e.g., sodium alkyl sulfate) and the water-soluble salts ofsulfonated monoglycerides of fatty acids having from 8 to 20 carbonatoms. Sodium lauryl sulfate (SLS) and sodium coconut monoglyceridesulfonates are examples of anionic surfactants of this type. Examples ofother suitable anionic surfactants are sarcosinates, such as sodiumlauroyl sarcosinate, taurates, sodium lauryl sulfoacetate, sodiumlauroyl isethionate, sodium laureth carboxylate, and sodium dodecylbenzenesulfonate. Mixtures of anionic surfactants can also be employed.Many suitable anionic surfactants are disclosed by Agricola et al., U.S.Pat. No. 3,959,458, issued May 25, 1976. In some embodiments, the oralcare composition may comprise an anionic surfactant at a level of fromabout 0.025% to about 9%, from about 0.05% to about 5% in someembodiments, and from about 0.1% to about 1% in other embodiments.

Another suitable surfactant is one selected from the group consisting ofsarcosinate surfactants, isethionate surfactants and tauratesurfactants. Preferred for use herein are alkali metal or ammonium saltsof these surfactants, such as the sodium and potassium salts of thefollowing: lauroyl sarcosinate, myristoyl sarcosinate, palmitoylsarcosinate, stearoyl sarcosinate and oleoyl sarcosinate. Thesarcosinate surfactant may be present in the compositions of the presentinvention from about 0.1% to about 2.5%, or from about 0.5% to about 2%by weight of the total composition.

Cationic surfactants useful in the present invention include derivativesof aliphatic quaternary ammonium compounds having one long alkyl chaincontaining from about 8 to 18 carbon atoms such as lauryltrimethylammonium chloride; cetyl pyridinium chloride; cetyltrimethylammonium bromide;di-isobutylphenoxyethyl-dimethylbenzylammonium chloride; coconutalkyltrimethylammonium nitrite; cetyl pyridinium fluoride; etc.Preferred compounds are the quaternary ammonium fluorides described inU.S. Pat. No. 3,535,421, Oct. 20, 1970, to Briner et al., where saidquaternary ammonium fluorides have detergent properties. Certaincationic surfactants can also act as germicides in the compositionsdisclosed herein.

Nonionic surfactants that can be used in the compositions of the presentinvention include compounds produced by the condensation of alkyleneoxide groups (hydrophilic in nature) with an organic hydrophobiccompound which may be aliphatic or alkylaromatic in nature. Examples ofsuitable nonionic surfactants include the Pluronics, polyethylene oxidecondensates of alkyl phenols, products derived from the condensation ofethylene oxide with the reaction product of propylene oxide and ethylenediamine, ethylene oxide condensates of aliphatic alcohols, acids, andesters, long chain tertiary amine oxides, long chain tertiary phosphineoxides, long chain dialkyl sulfoxides and mixtures of such materials.

Zwitterionic synthetic surfactants useful in the present inventioninclude derivatives of aliphatic quaternary ammonium, phosphonium, andsulfonium compounds, in which the aliphatic radicals can be straightchain or branched, and wherein one of the aliphatic substituentscontains from about 8 to 18 carbon atoms and one contains an anionicwater-solubilizing group, e.g., carboxy, sulfonate, sulfate, phosphateor phosphonate.

Suitable betaine surfactants are disclosed in U.S. Pat.No. 5,180,577 toPolefka et al., issued Jan. 19, 1993. Typical alkyl dimethyl betainesinclude decyl betaine or 2-(N-decyl-N,N-dimethylammonio)acetate, cocobetaine or 2-(N-coc-N,N-dimethyl ammonio)acetate, myristyl betaine,palmityl betaine, lauryl betaine, cetyl betaine, cetyl betaine, stearylbetaine, etc. The amidobetaines are exemplified by cocoamidoethylbetaine, cocoamidopropyl betaine, lauramidopropyl betaine and the like.The betaines of choice are preferably the cocoamidopropyl betaine and,more preferably, the lauramidopropyl betaine.

Precipitated silica tends to lessen the foaming of an oral composition.In contrast, heat treated precipitated silica, with its low reactivity,does not inhibit foaming, or does not inhibit foaming to the degree ofprecipitated silica. The lack of interference with surfactant componentscan impact the amount of surfactant used, which in turn may affect othervariables. For example, if less surfactant is needed to achieveacceptable consumer foaming, this may reduce irritancy (a known consumernegative of SLS), or could lower the composition pH, which could allowbetter fluoride uptake.

In some embodiments, polymeric mineral surface active agents are addedto mitigate negative aesthetics of these compounds. The polymericmineral surface active agents may be organo phosphate polymers, which insome embodiments are alkyl phosphate esters or salts thereof,ethoxylated alkyl phosphate esters and salts thereof, or non-ethoxylatedalkyl phosphates, or mixtures of alkyl phosphate esters or saltsthereof. In some embodiments, the polymeric mineral surface activeagents may be polycarboxylates or polyphosphates or co-polymers ofpolymeric carboxylates such as Gantrez.

In some embodiments, the composition may comprise a heat treatedprecipitated silica and be essentially free of SLS. Essentially freemeans that there is less than about .01%, by weight of the composition.In some embodiments, the composition may further comprise a surfactant,other than SLS, selected from the group consisting of a nonionicsurfactant, an anionic surfactant, a cationic surfactant, an amphotericsurfactant, a zwitterionic surfactant, and mixtures thereof. In someembodiments, the composition may further comprise a chelant. In someembodiments, the surfactant may be an amphoteric surfactant, such asbetaine, for example. In some embodiments, the composition may have aPCR of at least about 80. In some embodiments, the surfactant may be atleast about 50% available. In some embodiments, the composition has lessthan 3% of a surfactant, by weight of the composition. In someembodiments, the composition may further comprise a peroxide sourceand/or enzymes. Some embodiments may be a method of treating a dry mouthcondition by administering to subject's oral cavity an oral compositioncomprising heat treated precipitated silica, wherein the composition isessentially free of sodium lauryl sulfate.

Method of Use

The present invention also relates to methods for cleaning and polishingteeth. The method of use herein comprises contacting a subject's dentalenamel surfaces and oral mucosa with the oral compositions according tothe present invention. The method of treatment may be by brushing with adentifrice or rinsing with a dentifrice slurry or mouthrinse. Othermethods include contacting the topical oral gel, mouthspray, toothpaste,dentifrice, tooth gel, tooth powders, tablets, subgingival gel, foam,mouse, chewing gum, lipstick, sponge, floss, petrolatum gel, or dentureproduct or other form with the subject's teeth and oral mucosa.Depending on the embodiment, the oral composition may be used asfrequently as a toothpaste, or may be used less often, for example,weekly, or used by a professional in the form of a prophy paste or otherintensive treatment.

EXAMPLES Example I Heat Treated Precipitated Silica

Samples of commercially available precipitated silica materials wereheat treated for times and temperatures as shown below in Table 1.

TABLE 1 Material % Stannous Z-109 61.0 Z-109 - 2 hrs @ 600° C. 85.0Z-119 42 Z-119 - 2 hrs @ 600° C. 75.5 Z-119 - 1 min @ 900° C. 74.0Z-109 and Z-119 are precipitated silicas commercially available from theHuber Corporation (USA). As may be seen in Table 1, treatment of aprecipitated silica, Z-119, for about 1 minute at 900° improved thecompatibility with stannous (the percentage of stannous ion availableover time) at nearly the same level as by treating the same material fortwo hours at 600° C. The present invention therefore provides a similarbenefit at a significant lower energy cost.

Example II Heat Treated Precipitated Silica

Samples of commercially available precipitated silica materials wereheat treated for times and temperatures as shown below in Table 2. NMRwas then used to determine the level of Q2, Q3 and Q4 silanols with thereadings normalized to Q4. Compatibility with stannous in astannous-silica slurry was then measured by determining the amount ofstannous ion available in the slurry after one week at 60° C. Theresults are tabulated below, also in Table 2.

TABLE 2 Q4 Normalized Temp. Sn Values (%)* Q4 Normalized IntegralValues** Silica Time (° C.) (%) Q2 Q3 Q4 Q2 Q3 Q4 Total Z-119 None None51 7.28 62.54 30.18 3948 33903 16362 54213 Z-119 2 hrs. 200 7.45 57.934.65 3517 27339 16362 47218 Z-119 2 hrs. 400 64 10.52 53.39 36.09 476824204 16362 45335 Z-119 2 hrs. 600 66 9.67 43.14 47.19 3352 14958 1636234673 Z-119 2 hrs. 800 83 1.85 37.55 60.60 499 10137 16362 26998 Z-119None None 52 Z-119 2 min. 800 64.2 13.89 44.7 41.41 5489 17666 1636239517 Z-119 2 min. 900 75.5 13.31 50.03 36.67 5938 22324 16362 44624Z-119 2 min. 1000  80-90 13.36 46.88 39.77 5495 19289 16362 41146 Z-109None None 71 7.71 64.04 28.25 8168 67801 29907 105875 Z-109 2 min. 60014.07 48.02 37.91 11103 37883 29907 78892 Z-103 None None 7.99 56.8935.13 7361 52436 32377 92174 Z-103 2 min. 200 14.42 51.26 34.31 1361048366 32377 94353

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this written document conflicts with any meaningor definition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

While particular embodiments of the present invention have beenillustrated and described, it will be obvious to those skilled in theart that various changes and modifications may be made without departingfrom the spirit and scope of the invention. It is therefore intended tocover in the appended claims all such changes and modifications that arewithin the scope of the invention.

We claim:
 1. A process for improving the stability of precipitatedsilica particles with metal ions, said process comprising the steps of:a) providing one or more precipitated silica particles; b) subjectingthe precipitated silica particles to a temperature of at least about800° C. for a period of time to produce one or more treated precipitatedsilica particles; wherein the period of time is less than 5 minutes. 2.A process according to claim 1 wherein the temperature is from about850° C. to about 1050° C.
 3. A process according to claim 1 wherein thetemperature is from about 900° C. to about 1000° C.
 4. A processaccording to claim 1 wherein the period of time is less than or equal toabout 3 minutes.
 5. A process according to claim 2 wherein the period oftime is less than or equal to about 2 minutes.
 6. A treated precipitatedsilica produced by the process of claim
 1. 7. An oral care compositioncomprising one or more treated precipitated silica particles produced bythe process of claim 1 and a metal ion source.
 8. The composition ofclaim 7 wherein the metal ion source is a stannous ion source.
 9. Thecomposition of claim 8 wherein the stannous ion source is a stannoussalt selected from the group consisting of stannous chloride, stannousgluconate, stannous acetate, stannous tartrate, stannous oxalate,stannous sulfate, stannous citrate, stannous malonate, stannous lactate,stannous phosphate, stannous pyrophosphate, stannous bromide, stannousiodide, and combinations thereof.
 10. The composition of claim 8 whereinthe amount of stannous ion is from about 50 ppm to about 15,000 ppm. 11.The composition of claim 8 wherein the amount of stannous ion is fromless than about 10,000 ppm.
 12. The composition of claim 8 wherein thestannous ions have a compatibility of greater than 80% after two weeksof storage at 25° C.
 13. The composition of claim 8 wherein the stannousions have a compatibility of greater than 80% before use.
 14. Thecomposition of claim 13 wherein the stannous ions have a compatibilityof greater than 90% before use.
 15. The composition of claim 8 whereinthe stannous ion loss to heat treated precipitated silica is from about5 to about 50 ppm/1% load of heat treated precipitated silica.
 16. Thecomposition of claim 7 further comprising a chelant.
 17. The compositionof claim 16 wherein the chelant is selected from polymericorganophosphate compounds including ethoxylated and non-ethoxylated monoor di alkyl phosphates or phosphonates.
 18. The composition of claim 7further comprising one or more essential oils.
 19. The composition ofclaim 18 comprising two essential oils wherein the first essential oilis selected from the group consisting of acyclic or non-ring structuresand a second essential oil is selected from ring-containing structures.20. The composition of claim 7 further comprising a gel network.